We spend about one-third of our lives asleep. Why so much time in bed you may ask? There’s actually a good reason as to why sleep is important.
According to the Centers for Disease Control and Prevention (CDC) people who sleep less than 7 hours a night have higher risks of heart disease, stroke and heart attacks. They’re also more likely to develop cancer, arthritis, asthma and diabetes. Additionally, you’ll also be more prone to depression.
You may also want to know that being a short sleeper (sleeping less than 7 hours/night) also makes you more likely to be obese, physically inactive, a smoker and excessive drinker.
The thing is, nearly 40% of people sleep less than 7 hours per night. Interestingly, if you live in the east coast, you’re more likely to be a short sleeper. The worst offenders being those between the ages of 25 and 54.
What Happens When We Sleep?
Sleep was once thought to be a passive state. After all, your body doesn’t seem like it’s doing much while asleep. At least, that’s what it seems on the outside.
In reality, your brain is very busy during sleep. And, it uses chemical signals to regulate and repair your tissues and organs. This allows you to wake up refreshed and re-energized the next morning.
In fact, sleep plays an important role in keeping you healthy. Among them include:
- Repair your tissues to help you get stronger or relieve pain.
- Promote growth in children and adolescents by releasing growth hormone.
- Regulate your body’s temperature and help you conserve energy.
- Control your metabolism.
- Keep your immune system healthy.
- Heal and repair your heart and blood vessels.
- Regulates hormones that are related to hunger, appetite and ultimately your weight.
- Consolidates your memories and declutters your brain.
This is why not getting enough sleep is harmful to your health. Lack of sleep limits your body’s ability to repair itself and recover. Over time, this causes it to wear out.
Our Sleep Cycle: The 5 Stages of Sleep
To perform all these functions, your body goes through different phases during sleep. In each phase, it experiences varying physiological changes. These range from your eyes darting rapidly back and forth to paralyzing your muscles and lowering your blood pressure. All of these happen so it can produce the desired effects, be in consolidate memory or restore energy.
In all, there are 5 stages of sleep. These are stages 1, 2, 3, 4 and REM (Rapid Eye Movement). Additionally, you cycle through these 5 stages over and over through the 7 to 8 hours you’re in bed.
On average, you’ll go through 4 to 5 cycles a night. Each complete cycle, running from stage 1 to REM sleep, lasts about 90 to 120 minutes.
This is the same thing that happens when you nap. The only difference is, because naps are shorter, you may complete only one cycle or less than that.
Stage 1 Sleep
Stage 1 sleep is when you transition from being awake to going to sleep. It is that initial period when you start to doze off and lasts between 2 to 10 minutes. During this time, you’ll drifting in and out of sleep. Your eyes also start to move more slowly while your muscles begin to relax.
Stage 2 Sleep
Stage 2 is the onset of sleep. It takes up almost half of all the time you spend asleep. Here, you’re still in light sleep. And, like stage 1 you’re still in NREM (Non-Rapid Eye Movement) sleep.
During this time, you heart rate slows down, and you lose awareness of your surroundings. Your body’s core temperature also drops while your brain waves slow down, and eye movement stops.
Stage 2 is when your body recovers energy. It is also when your motor skills and ability to do complex tasks improve.
Stages 3 and 4 Sleep
In stages 3 and 4 you go into deep sleep, or what’s called slow wave sleep. You spend about 30% of sleep here.
At this point, it’s harder to wake you up. And, waking up during this time also causes sleep inertia, or that groggy feeling you sometimes experiences after longer naps.
Stages 3 and 4 still belong in NREM sleep. That is because there’s still no eye movement.
During this time, your brain waves slow down even more. And, your blood pressure drops. Breathing also becomes slower. But, it gets deeper and more rhythmic.
Slow wave sleep is where you experience the most restorative sleep. It is also when hormones are released. Among them are those that help regulate hunger and appetite. It is also when growth hormone is secreted. This helps repair your muscles and tissues.
Additionally, slow wave sleep is when your brain consolidates useful information and discards the clutter. This allows it to “connect the dots” between bits of information you’ve learned.
REM sleep is very different from all the other stages of sleep. This is why it is often classified on its own. During REM sleep, your eyes dart back for forth at a rapid rate. This is where it gets its name, Rapid-Eye Movement (REM) sleep.
You typically spend about 20% of sleep time in REM sleep.
REM sleep is the opposite of NREM sleep in more ways than one. During NREM sleep, your body heals while your mind rests. In REM sleep on the other hand, your brain is very active while your body is immobilized.
As such, they complement one another.
REM sleep is also when dreaming happens. It also works on the short-term memory you’ve just solidified and moves into your brain’s hippocampus. This allows you to develop long term memories.
Besides improving memory, REM sleep also helps boost your creativity, spatial orientation and perception.
Negative Effects of Lack of Sleep
Effects of Sleep Deprivation
1. It Increases Your Risk of Errors and Accidents
Sleep deprivation no matter what the severity makes you more susceptible to making mistakes. And, depending on what task you’re carrying out, the errors can be extreme.
For example, drowsy driving may not be punishable by law like other forms of impaired driving, but it has been estimated that driving while tired is responsible for at least twenty percent of crashes (1).
The accidents associated with lack of sleep causes issues in the hospital as well. Conservative estimates show 50,000 deaths each year result from medical errors, many of which stem from insufficient sleep.
On a more catastrophic scale, oil spills, nuclear meltdowns, and space shuttle failures alike were connected to individuals in charge having to make important decisions under conditions of significant sleep deprivation (1).
Often when sleep deprivation has been linked to a terrible accident it has spurs regulations being enacted to ensure proper sleep for those who work in the industry to prevent future mishaps. This should make you think about what mistakes you may have made because of a lack of sleep.
2. You’ll Gain Weight
There has been a proven association between how long you’re sleeping and how your body puts on the pounds.
Studies out of the Mayo Clinic have shown that people who consistently sleep less than five hours a night will have a greater likelihood of weight gain when compared with those who get the required amount of sleep a night (2).
We aren’t just talking about a pound here or there either. Ladies who were sleeping less than six hours a night were more likely to gain up to eleven more pounds when compared next to ladies who slept an adequate amount (2).
This weight gain occurs because sleep affects the amount of hunger regulating hormones that stimulate your appetite. In combination with the lethargy, you feel making you less active it is a recipe for weight gain.
So, if you wish to overcome this issue and feel better in general getting the recommended out of sleep is key!
3. It Affects Your Ability to Concentrate
The ideal amount of sleep varies on age, gender, and health status. Typically, a healthy adult will require seven to eight hours of sleep a night. Teens will require about nine hours of sleep per night and children will require at least nine hours of sleep.
But, this number varies greatly based on age. Whatever the amount of sleep you require is, getting less than the magic number will decrease your overall concentration and slow down your thought process (3).
This happens in part because of decreased cardiorespiratory function that is observed when you are sleep deprived. This minor decrease lowers oxygen levels in the brain which promotes the decrease in cognitive speed and inability to concentrate (4).
4. Increased Risk of High Blood Pressure, Heart Disease and Diabetes
How little you sleep could be negatively impacting your blood pressure, if you’re not getting enough of it. Increasing the amount of sleep you get to an adequate level per night will help lower your systolic blood pressure, especially when you are diagnosed as pre-hypertensive or hypertensive. (5).
Lack of sleep causes the body to put on more weight as previously mentioned. The extra weight will contribute to the increased likelihood for hypertension. This increased hypertensive risk goes hand-in-hand with the development of heart disease especially in adult women (6).
This vicious cycle can lead to the development and worsening of many illnesses that plague millions of Americans. Fortunately, there are ways to lower your risks of hypertension and heart disease and it could be as simple as getting the right amount of shut-eye.
5. Higher Risk of Diabetes
There is astounding evidence that your body responds to lack of sleep in a manner that mimics and can catalyze the development of insulin resistance, also known as pre-diabetes (7).
As such, it is especially important for those who are pre-diabetic or diabetic to get an adequate amount of sleep since any lack of energy they feel will make them more likely to experience a deficit of insulin.
That lack of energy makes the body work harder to maintain its system. And, in the process, depleting insulin far faster than a non-diabetic person would (7).
Since you now know that sleep deprivation increases your appetite and impairs your ability to lose weight it is easy to see how it can also encourage the development of diseases like diabetes.
6. You’ll Age Faster
For years you’ve probably been hearing that lack of sleep makes you look older faster from beauty magazines and anti-aging creams alike.
Well those claims aren’t just skin deep. In fact, studies have shown metabolic and hormonal shifts stemming from sleep deprivation (8). These metabolic and endocrine shifts are identical to the shifts that occur with aging and may trigger faster and more severe onsets of age-related conditions such as memory loss, diabetes, and hypertension.
Not only do you internally age faster, but lack of sleep can make you look older since your skin’s ability to repair itself weakens due to a decrease in elasticity.
This sleep decrease in elasticity from lack of sleep increases the appearance of fine lines, sagging skin, and uneven pigmentation (9).
7. Your Memory Will Suffer
Sleep deprivation not only causes an increase in accidents related to the decrease in mental functioning, but it can make you more forgetful and speed up the degeneration of memory with age.
As your focus and overall awareness decreases with lack of sleep, it becomes much harder for your neurons to coordinate information resulting in the inability to recall previously learned information (1).
Furthermore, when you are sleep deprived you typically do not get the right amount of slow-wave sleep, which is the restorative sleep that plays an operative role in memory.
This inhibition of memory can be especially detrimental long-term to older adults with aging brains. The same inhibition can be detrimental to young adults as it inhibits learning, so if you can’t decide between sleep or studying all night, you should probably just sleep.
8. Lack of Sleep Makes You More Irritable
It’s no secret that when you’re sleep deprived you are not as happy as you normally are. And, maybe things that typically wouldn’t bother you, really grinds your gears.
In fact, when a group of people are under sleep deprivation conditions for a week, they reported increased feelings of aggression and irritability, significantly higher to their well-rested peers (10).
This is in part due to the increase in circulating stress hormones within your body when you do not sleep enough. And, while trying to catch up a good night’s sleep with a nap will decrease the amount of stress hormone slightly, it won’t always be enough to improve overall mood for the rest of your day (11).
Individuals who must function while experiencing a period of decreased mood will feel more tired easier thus worsening the irritability felt from sleep deprivation.
We have already discussed the cognitive and physical impacts of sleep deprivation such as memory impairment, weight gain, irritability, and hypertension. But, there are psychological impacts as well, like depression and other mood disorders.
Studies have shown that recurring sleep deprivation can cause neurochemical shifts within the brain that cause psychological disorders like depression (12).
Unfortunately, the cycle is bidirectional. Not only can sleep deprivation cause depression, but depression can cause sleep deprivation as well.
Sleep deprivation especially in young adults increases depressive symptoms greatly, the longer the deprivation continues the neurological imbalances continue to worsen (12).
Health Benefits of Getting Enough Sleep
1. Less Stress
As we mentioned earlier there are more circulating stress hormones in your body when you enter a state of sleep deprivation. (11)
Sleep deprived people have been proven to see an increase in night time cortisol secretion. And, to worsen the problem, cortisol levels drop even slower in a sleep deprived person than they do a well-rested individual (13).
Meanwhile, elevated amounts of stress hormones like norepinephrine and cortisol leave your body in a fight-or-flight mode that will only make it harder to sleep the more tired you get (11,13).
While the circulating stress hormones may not make you feel horribly different, they will increase the likelihood that you will develop obesity or diabetes if not regulated. Which is why it’s much better to call it a night early when you’re tired from not sleeping the night before.
2. You’ll Be More Alert and Have More Energy
Like your cell phone your brain runs on energy. Adenosine triphosphate (ATP) is the energy your body produces to carry out all of its essential functions like thinking, digesting, and breathing.
When you sleep, your body’s ATP is replenished in a cyclic manner (14). The ATP production varies based on the different sleep stages. Some produce more ATP while others produce less.
That said, when you wake up from a long night of rest, you feel more alert because you woke up from stage 2 of your sleep cycle wherein the night before produced plenty of ATP (15).
But, if you do wake up feeling groggy, it is often because you awoke from a deep sleep stage.
To avoid this, try sleeping an additional fifteen minutes to awake from a lighter sleep stage. This will let you enjoy the notable increase in ATP sooner.
3. Your Brain Will Work Better
While it may not seem like it, your brain is very active during sleep. During this time, it consolidates your thoughts, experiences and memory. This allows you to piece everything you know together. And, in doing so, allows you to see the “big picture” or gain better perspective on different things.
It is the reason why you sometimes wake up with a new idea. Or, are able to come up with a solution to a problem that you couldn’t solve before going to bed.
Similarly, while you slumber, the flow of cerebrospinal fluid in your brain increases. This helps clear out toxins and waste products that have build up during the day time.
In doing so, it allows you to think clearly. In the long-term, it also protects your mind from cognitive issues like dementia and Alzheimer’s Disease.
4. Stronger Immune System to Prevent Disease
There are many factors that modulate your immune system and ensure that it is functioning properly to protect you from illnesses and foreign invaders. One of the most important factors is interleukin-6.
When you sleep less, IL-6, a proinflammatory cytokine, decreases (11). While typically a decrease in a pro-inflammatory cytokine would be welcome, IL-6 serves to inhibit the function of other inflammatory compounds that create a stress response and weaken the immune system.
As such, sleeping more and sleeping well at night is the best way to fight off a cold and get well sooner.
5. It Will Make You Happier
Of course, you will be in a happier mood when you get more sleep at night and have more energy. But, you may not know why exactly.
We discussed the restorative benefits of sleep, including the ATP production, which gives you more energy to better your mood (14).
As we just discussed with immune function, the proinflammatory cytokine Interleukin-6 remains at a healthy level when you sleep better.
Since that cytokine inhibits the production of other inflammatory responses, you will feel happier when you have more of it (11).
Many inflammatory responses in your body contribute to the stress response you feel. As such, when you get enough sleep and stress responses are lower, you’ll feel much happier and better about yourself.
6. Improves Relationship with Others
Getting adequate amounts of sleep will lead you to having a better relationship with your partner in many ways.
Partners who sleep more experience the decrease in hormonal stress responses we previously discussed. Thus, leaving them feeling happier than those who don’t sleep well (14).
Not only will you feel happier, but you will feel closer with your partner and more secure in your relationship (18).
Since you will be feeling happy and confident in your relationship you and your partner will be able to grow more and have a great time with one another.
7. Good Sleep Helps You Lose Weight
We briefly discussed that appetite regulating hormones are affected when you are sleep deprived, by that logic you know that they’re better regulated by quality sleep negating the weight-gain effects that sleep deprivation can promote.
When you are well-rested, leptin the appetite suppressing hormone made by fat calls circulates at the proper concentration decreasing your cravings for energy dense, less-than-great for your foods (13).
Ghrelin, the hormone that makes you hungry will increase with the less sleep you get causing you to eat more than you should. So, if at night you are hankering for that midnight snack, going to sleep will help fight off the pounds.
8. Sleep Lets Your Body Repair Itself Properly
Sleep is restorative and can help your brain assist your body in repairing itself. While we have previously discussed that good quality sleep is essential to cognition, memory, and decision making, it is important to physical restoration as well (17).
While REM sleep is more focused on brain repair, the non-REM stages focus more on healing wounds, neutralizing neurotoxins, and repairing nerve tissues.
This occurs by improving the immune function and protein synthesis within the body. If you have an injury or ailment the best way to naturally help yourself is to sleep early, allowing your body more time to repair damaged tissues.
9. Curb Inflammation
If you stand on your feet for a long period of time and get home from a long day of work with swollen joints or ankles, then more sleep may benefit you greatly. Once you get into a habit of poor sleep your liver begins to produce more C-reactive proteins due to inflammation (16).
Inflammatory responses typically serve to dispel infections and foreign substances from the body, but when they create inflammatory response because of lack of sleep they cause more harm than good, detracting from immune function (16). The more sleep you get will help decrease this inflammatory reaction greatly.
How Much Sleep Do You Need?
In general, adults and young adults need 7 to 9 hours of sleep per night. As shown in the chart, the number of hours you sleep depends on your age.
Infants and toddlers need the most sleep, averaging around 12 to 15 hours a day. This number goes down by the time you get to your teens, settling at around 9 to 10 hours.
By the time you’re 18 years old all the way up to 65, you’ll typically need between 7 and 9 hours of sleep. That number goes down again, albeit only very slightly as you get older.
That said, these figures are based on the general population. Research suggests that the actual number of hours you need to sleep will depend on a few things. These include your genes, sleep quality, and how you’ve been sleeping in the past days and weeks among other things. Thus, it’s very subjective.
Similarly, research shows that only 3% of people are meant to sleep 6 hours per night. The rest of us in the 97% will have to settle for the regular 7 to 9 hours of shuteye nightly.
One good way to figure out the exact number of hours you need to sleep is work backwards. If you have to wake up at 7:00 in the morning. Try going to bed by 10:45 pm. This includes the 15 minutes it takes for us, on average, to fall asleep.
Depending on how you feel in the morning, you can adjust your bedtime earlier or later. Keep adjusting the time you go to bed until you get that “sweet spot” where you get a full night’s sleep and wake up refreshed in the morning.